JERUSALEM — Ben Deri says he was just following orders as an Israeli border police officer when he opened fire on Palestinian protesters in 2014.

But his gun was loaded with live ammunition, not the rubber bullets he’d been ordered to use, an investigation later found. His shots left two people dead and one seriously injured.

Four years later, almost to the day, Deri started an eight-month jail sentence last month for causing the death of one of the Palestinians, 17-year-old Nadeem Nowarah, by negligence. Deri, 24, was also ordered to pay Nowarah’s family $14,000 in compensation.

The case is exceptional because Israeli security forces are so rarely taken to court for killing or abusing Palestinians.

The eventual punishment, reached via a plea bargain, left both sides unhappy. Nowarah’s family was outraged that their son’s killer was convicted of negligence, not murder. Deri was dismayed because, he felt, the government that put him at that protest four years ago had abandoned him.

Deri had been doing military service in the border police, a hybrid military unit under the auspices of the national police force, responsible for keeping order. Because he was essentially a police officer, he was tried in a civilian court, putting him face to face with Nowarah’s family.

Speaking in recent, separate interviews, Nowarah’s father, Siam, and Deri both expressed profound regret about the events that brought them into such unusually intimate contact.

It was largely Siam’s determination to seek justice for his son that brought about the trial. The Israeli military initially denied any wrongdoing, and Israeli lawmakers tried to cast doubt on the Palestinian version of events.

‘‘I think he saw me fighting, he saw a family fighting to get justice for the death of their son, and that changed things for him a little,’’ Siam Nowarah said. ‘‘I felt my words had an impact on him and will stay with him for the rest of his life.’’

Deri, speaking a week before he was jailed, said he decided to accept the plea bargain against the advice of his lawyer, because he wanted to ‘‘just get it over.’’ State prosecutors have been pushing for a harsher sentence.

‘‘I’ve been in a very difficult emotional state through these past four years,’’ he said. ‘‘I am just very, very disappointed with the system. I gave [the army] three years of my life. Then something happened, and they just abandoned me.’’

The shooting took place during the annual Nakba Day protests, when Palestinians mark what they call the catastrophe of Israel’s creation when 700,000 Palestinians were expelled or forced to flee their homes.

Siam Nowarah said his son was a normal teenager, the joker of the family who listened to Western pop music stars like Lil Wayne and Justin Bieber. The family had no idea that Nadeem had gone to the annual protest in the West Bank village of Beitunia.

One set of grainy footage, taken by a CNN photographer, shows Deri cocking his gun, another, captured on CCTV cameras, shows Nowarah, wandering alone on the edge of the protest with his school bag on his back, suddenly fall to the ground. Siam later retrieved the Israeli-issued bullet from his son’s backpack.

Amit Gilutz, a spokesman for the Israeli human rights group B’Tselem, said that because of the video footage, it was impossible for the Israeli judicial system to ignore this case. But Gilutz stressed that only a small handful of such cases get to court.

‘‘It is very rare for Israeli security personnel to be indicted for hurting Palestinians,’’ Gilutz said. A report published by B’Tselem in November noted that out of 739 cases in which soldiers killed, injured or beat Palestinians or destroyed their property, 3 percent led to an indictment.

The elder Nowarah, who had worked as a hairdresser, said life had been ‘‘rosy’’ before the shooting. ‘‘I only saw the beautiful side of life,’’ he said during the interview at his middle-class home in the West Bank city of Ramallah. ‘‘Now I see how people suffer.’’

Afterward, he said, he sold his chain of hairdressing salons sold to pay for the cost of pursuing justice, something few Palestinians dare to do.

Four years on, he looks tired from the fight but is still well kept in a button-down shirt and dress pants. Hehe offers counseling to other Palestinian children and their families caught up in the violence through a nonprofit group headquartered in one of his former salons. He urges them to avoid confrontation with Israeli soldiers.

‘‘I tell them that they should not want to die for Palestine but want to live for Palestine,’’ Nowarah said.

During an interview in Deri’s apartment in the Israeli city of Rishon LeZion, he sat nervously on the edge of a sofa. Dressed casually in a T-shirt and shorts, his hair shaved to his scalp, Deri said no police officer could ever believe he would find himself behind bars. He said he still replays the events of four years ago, trying to understand whether they were inevitable.

‘‘They prepare you, train you and send you out on a mission. You do what you are taught, follow the rules, know when you are on duty during unrest. But the minute someone is killed, you are very sorry, because it should not happen unless there is a real need,’’ he said. ‘‘You get to a point where you ask if you had a choice.’’

In a shaky, agitated voice, he continued: ‘‘A person was killed, and I am sorry for what happened and for the family. It was not something that I planned and not something I am happy about.’’

Deri was still living at home with his parents, but they were not present at the time of the interview. Instead, it was closely monitored by Ran Carmi, a right-wing Israeli activist who supports former soldiers on trial for killing Palestinians. The soldiers are the real victims, Carmi says.

‘‘It was not his fault,’’ Carmi said. ‘‘We are angry that a soldier is being put on trial for actions that he was sent to carry out. The state that sends them into battle should not abandon them in the field.’’

Carmi has helped Deri and his parents raise money to pay for the trial, legal costs for a top notch, well-known lawyer, expenses for expert ballistic witnesses flown in from abroad and for the compensation he has to pay to the Nowarah family. There is also an online fund-raising campaign, ‘‘We are all Ben Deri,’’ trying to raise about $42,000. A month after it was set up, it had raised a quarter of its goal.

Yehuda Shaul of Breaking the Silence, an Israeli group that gathers anonymous testimony from past and current Israeli combat soldiers, was also critical of Deri’s trial but for very different reasons. He said that such trials allow Israelis to ‘‘whitewash our consciences’’ by deflecting the role of the military and focusing on the actions of the individual.

‘‘First, we get to say that the soldier’s behavior was exceptional; and second, we try to justify the lack of accountability of the system itself,’’ Shaul said. He added: ‘‘We should not forget that individuals must take responsible for what they’ve done. There should not be a get-out-of-jail-free card for any soldiers.’’